This week, people are wondering about WikiLeaks, with some asking if Twitter has blocked #wikileaks, #cablegate or other related topics from appearing in the list of top Trends.

The answer: Absolutely not. In fact, some of these terms, including #wikileaks and #cablegate, have previously trended either worldwide or in specific locations.

Given the widespread confusion about #wikileaks, we’d like to offer a longer explanation of how we measure Trends on Twitter, and why some popular topics may not make the list.

What is a Trend? Twitter Trends are automatically generated by an algorithm that attempts to identify topics that are being talked about more right now than they were previously. The Trends list is designed to help people discover the ‘most breaking’ breaking news from across the world, in real-time. The Trends list captures the hottest emerging topics, not just what’s most popular.

What makes a trend a Trend? Twitter users now send more than 95 million Tweets a day, on just about every topic imaginable. We track the volume of terms mentioned on Twitter on an ongoing basis. Topics break into the Trends list when the volume of Tweets about that topic at a given moment dramatically increases.

Sometimes a topic doesn’t break into the Trends list because its popularity isn’t as widespread as people believe. And, sometimes, popular terms don’t make the Trends list because the velocity of conversation isn’t increasing quickly enough, relative to the baseline level of conversation happening on an average day; this is what happened with #wikileaks this week.